Releasing Internal Table Memory

It is a well known fact, that you release the memory occupied by an internal table using either CLEAR or FREE, where FREE releases also the initial memory area. You normally use CLEAR, if you want to reuse the table and you use FREE, if you  really want to get rid of it and don't want to refill it later on. Assigning an initial internal table to a filled internal table does also release the target table's memory in the same way as CLEAR does.

But last week a colleague pointed out to me that it is not such a well known fact that deleting lines of internal tables with DELETE normally does not release the memory occupied by the deleted lines. Instead, there seem to be people deleting lines of internal tables in order to release memory. Therefore as a rule:

Mocking DAOs with ABAP Test Double Framework

Introduction

The sample below is very basic and no real business logic is included because it focuses on the concepts. For the dependency injection of the daos I used an interface for two reasons. First when more complicated or variants of Daos are needed the interface provides more flexibilty and the ABAP test double framework currently only can mock interfaces.

If you have suggestions, hints or question feel free to comment this document as I am keen on improve my concept, since it will not be the last time I have to write a Dao.